Support for catalysts, process for the manufacture of a precurso

Details Support for catalysts, process for the manufacture of a precurso Support for catalysts, process for the manufacture of a precurso

1996-01-29

1998-12-15

Nagumo, Mark

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

526106, 526113, 526118, 526130, 502154, 502172, 502200, 502201, 502210, 502214, 502405, 423305, 423306, 4233271, C08F 402, C08F 424

Patent

active

058498524

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a support for catalysts containing at least two constituents chosen from silica, alumina and aluminium phosphate, in particular a ternary support consisting of silica, alumina and aluminium phosphate. The invention also relates to a process for the manufacture of a precursor gel of such a support, containing silica, as well as to a process for manufacturing a support from the said precursor gel. Additionally, it relates to catalysts for the polymerization of olefins containing chromium on such a support, as well as to the use of these catalysts in the polymerization of olefins.
Supports consisting of mixtures of oxides are known. For instance, the patent application EP-A-283 815 describes compositions containing alumina and silica suitable for the treatment of liquid hydrocarbons. The patent application FR-A-2 315 997 describes supports containing alumina and aluminium phosphate suitable for the conversion of hydrocarbons.
U.S. Pat. No.4,758,544 (Chevron Research Company) describes a support for catalysts composed of alumina, aluminium phosphate and silica having a mean radius of the pores of 10 to 300 .ANG., a specific surface of 50 to 400 m.sup.2 /g and a pore volume of 0.1 to 1.5 cm.sup.3 /g which is suitable for the hydrodenitrification of oils.
U.S. Pat. No. 3,342,750 (Esso) discloses the preparation of supports for catalysts, containing aluminium phosphate and silica, whose specific surface is, for example, equal to 403 m.sup.2 /g and the pore volume to 0.77 cm.sup.3 /g.
A description is given, in Example IA of patent application GB-A-2,090,158 (Phillips Petroleum Company), of a process for the preparation of a support for catalysts composed of silica and aluminium phosphate, according to which a solution containing isopropanol, water, phosphoric acid, silicon ethoxide and sulphuric acid is prepared, aluminium nitrate, aminodihydroxyphosphine and chromium nitrate are added thereto and ammonium hydroxide is introduced therein to produce cogelling.
These known supports show a high degree of heterogeneity and consequently crystallize very quickly when they are calcined at temperatures greater than 700.degree. C. Moreover, these supports do not simultaneously combine a high specific surface with a high pore volume. The result thereof is that these known supports do not make it possible to manufacture chromium-based catalysts for the polymerization of olefins which show, at the same time, a high catalytic activity, a low induction period for the polymerization and a good response to hydrogen. Moreover, they do not make it possible to obtain polyolefins having a molecular mass distribution which can be adjusted between a moderately broad distribution and a very broad distribution for a given melt index and they generally give rise to a significant formation of oligomers.
The invention overcomes these disadvantages by providing a new support, of homogeneous and amorphous structure, which is resistant to crystallization, which simultaneously possesses a high pore volume and a high specific surface, and which, when it is used as a support for a chromium-based catalyst in the polymerization of olefins, confers the following combined advantages on this catalyst: polyolefins having: broad distribution and a very broad distribution for a given melt index, and
Consequently, the invention relates to a support for catalysts containing at least two constituents chosen from silica, alumina and aluminium phosphate; according to the invention, the support has a specific surface of 100 to 800 m.sup.2 /g, a crystallization temperature greater than or equal to 700.degree. C. and a pore volume of 1.5 to 4 cm.sup.3 /g, the specific surface (SS) and the pore volume PV) corresponding to the following relationship: surface, expressed in m.sup.2 /g, and of the pore volume, expressed in cm.sup.3 /g.
According to the invention, the specific surface (SS) of the support is measured according to the BET volumetric method of British standard BS 4359/1 (1984); the pore volume (PV) is the sum of the pore

REFERENCES:
patent: 3342750 (1967-09-01), Kearby
patent: 4364839 (1982-12-01), McDaniel et al.
patent: 4721696 (1988-01-01), Kidd
patent: 4758544 (1988-07-01), Plesko et al.
patent: 4806513 (1989-02-01), McDaniel et al.

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